{"gene":"METTL17","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2019,"finding":"METTL17 localizes to mitochondria via an N-terminal targeting sequence, specifically interacts with 12S mitochondrial ribosomal RNA (mt-rRNA) and small subunit mitoribosomal proteins (MSSUs), and is an S-adenosyl methionine (SAM)-binding protein. Loss of METTL17 reduces m4C840 (~70%) and m5C842 (~50%) modifications on 12S mt-rRNA, identifying METTL17 as the first known regulator of m4C840. METTL17 loss destabilizes 12S mt-rRNA and associated MSSU proteins, impairing mitochondrial ribosome function and translation of mitochondrial protein-coding genes in a SAM-binding-dependent manner, causing defects in oxidative phosphorylation.","method":"CRISPR knockout screen, subcellular fractionation/localization, RNA-protein interaction assays, SAM-binding assays, mass spectrometry-based RNA modification quantification, mitochondrial translation assays, metabolomics","journal":"FASEB journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (localization, RNA binding, biochemical SAM-binding, quantitative modification mapping, translation assays) in a single focused study","pmids":["31487196"],"is_preprint":false},{"year":2024,"finding":"METTL17 binds to the mitoribosomal small subunit (mt-SSU) during late assembly and harbors a previously unrecognized [Fe4S4]2+ cluster required for its stability. Loss of the Fe-S cluster destabilizes METTL17. METTL17 acts as an Fe-S cluster checkpoint: it promotes translation of Fe-S cluster-rich OXPHOS proteins only when Fe-S cofactors are available. METTL17 overexpression rescued mitochondrial translation and bioenergetic defects in frataxin (FXN)-deficient cells.","method":"Quantitative proteomics, comparative sequence analysis, site-directed mutagenesis, biochemical assays, cryo-electron microscopy (cryo-EM), overexpression rescue experiments","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure, mutagenesis, biochemistry, and functional rescue in a single rigorous study with multiple orthogonal methods","pmids":["38199006"],"is_preprint":false},{"year":2024,"finding":"METTL17 governs mitochondrial RNA methylation (including m4C, m5C, m3C, m7G, and m6A marks) in colorectal cancer cells. METTL17 inhibition reduces these modifications, impairs translation of mitochondrial protein-coding genes, disrupts mitochondrial function and energy metabolism, and increases intracellular and mitochondrial lipid peroxidation and ROS, sensitizing cells to ferroptosis.","method":"siRNA/shRNA knockdown, MeRIP/epitranscriptomic profiling, mitochondrial translation assays, ROS/lipid peroxidation measurement, xenograft tumor models, AOM/DSS-induced CRC model","journal":"Redox biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple functional readouts and in vivo models, single lab, mechanistic interpretation relies partly on prior work","pmids":["38377789"],"is_preprint":false},{"year":2023,"finding":"Using MALDI-TOF mass spectrometry, direct methyltransferase activity of METTL17 on a 12S rRNA target region during mitoribosome assembly was tested. The results did not confirm direct methyltransferase activity of METTL17 on this substrate under the conditions tested, suggesting METTL17 may regulate modifications indirectly rather than as a direct methyltransferase.","method":"MALDI-TOF mass spectrometry of putative METTL17 substrate (12S rRNA region)","journal":"Acta naturae","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single method, single lab, negative/ambiguous result about direct enzymatic activity","pmids":["38234605"],"is_preprint":false},{"year":2025,"finding":"METTL17 stability is regulated post-translationally through a SIRT5-RNF126 axis: the E3 ubiquitin ligase RNF126 ubiquitinates METTL17 at K116, targeting it for degradation, while SIRT5 acts as a desuccinylase removing succinylation at K274 of METTL17, thereby facilitating RNF126-mediated ubiquitination and degradation. METTL17 sustains mitochondrial OXPHOS by positively regulating electron transport chain components NDUFA2, NDUFS1, SDHB, UQCRB, and MT-CO2.","method":"Co-immunoprecipitation, mass spectrometry, lentiviral knockdown/overexpression, site-directed mutagenesis (K116, K274), ATP/ROS/mitochondrial membrane potential assays, xenograft tumor models","journal":"Cell & bioscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, mass spectrometry, mutagenesis of modification sites, functional rescue; single lab","pmids":["42021405"],"is_preprint":false},{"year":2025,"finding":"METTL17 promotes RNA methylation of STAT1 mRNA, inhibiting STAT1 mRNA and protein stability, thereby suppressing M1 macrophage polarization and inflammatory response. METTL17 knockdown promoted M1 macrophage polarization and enhanced inflammatory signaling.","method":"RT-qPCR, MeRIP assay, Western blot, flow cytometry, EdU proliferation assay, siRNA knockdown","journal":"Critical reviews in eukaryotic gene expression","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, limited mechanistic validation, MeRIP without site-specific mapping or rescue of specific modification","pmids":["39957595"],"is_preprint":false},{"year":2025,"finding":"Structural and molecular dynamics analysis of Mettl15 and Mettl17 in Trypanosoma brucei integrated with mammalian homolog data reveals that Mettl17 binds the mt-SSU at an early assembly stage and acts as a platform for Mettl15 recruitment. Release of Mettl17 allows a conformational change of Mettl15 for substrate recognition, and after methylation Mettl15 adopts a loosely bound state leading to its replacement by initiation factors, linking early and late pre-mitoribosome assembly stages.","method":"Cryo-EM structural data (T. brucei), molecular dynamics simulations, integration with mammalian homolog structural data","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — structural data plus MD simulations, model organism (T. brucei) with mammalian integration; preprint, not yet peer-reviewed","pmids":["bio_10.1101_2024.12.18.629302"],"is_preprint":true},{"year":2025,"finding":"METTL17 interacts directly with bufalin (identified by human proteomic microarray and molecular docking), and METTL17 promotes oral cancer progression in vitro and in vivo through activation of the JAK1/STAT3 signaling pathway. Bufalin downregulates METTL17 expression and reverses its pro-tumorigenic effects.","method":"Human proteomic microarray, molecular docking, CCK-8, wound healing, transwell, Western blot, in vivo xenograft","journal":"European journal of medicinal chemistry","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, pathway placement inferred from downstream markers without direct mechanistic link between METTL17 mitoribosomal function and JAK1/STAT3","pmids":["41005192"],"is_preprint":false}],"current_model":"METTL17 is a mitochondria-localized SAM-binding protein that associates with the mitoribosomal small subunit (mt-SSU) during late assembly, harbors a [Fe4S4]2+ cluster essential for its stability, regulates m4C840 and m5C842 modifications on 12S mt-rRNA (and possibly additional marks), and acts as an Fe-S cluster checkpoint that licenses translation of OXPHOS proteins only when Fe-S cofactors are available; its stability is further controlled post-translationally by SIRT5-mediated desuccinylation at K274 and RNF126-mediated K116 ubiquitination, and in the broader assembly pathway it cooperates with Mettl15 by serving as a platform for Mettl15 recruitment before being released to allow progression to late assembly."},"narrative":{"mechanistic_narrative":"METTL17 is a mitochondria-localized, SAM-binding protein that supports assembly and function of the mitoribosomal small subunit and thereby enables translation of mitochondrially-encoded OXPHOS components [PMID:31487196, PMID:38199006]. It is imported via an N-terminal targeting sequence, binds 12S mt-rRNA and small-subunit mitoribosomal proteins during late assembly, and its loss destabilizes 12S mt-rRNA and associated proteins, impairing mitochondrial translation and oxidative phosphorylation in a SAM-binding-dependent manner [PMID:31487196]. METTL17 loss reduces the m4C840 and m5C842 modifications on 12S mt-rRNA, identifying it as the first known regulator of m4C840, although a dedicated test of direct methyltransferase activity on the 12S region did not confirm catalysis, indicating it may govern these marks indirectly [PMID:31487196, PMID:38234605]. METTL17 harbors a [Fe4S4]2+ cluster required for its own stability and functions as an Fe-S cluster checkpoint that licenses translation of Fe-S-rich OXPHOS proteins only when Fe-S cofactors are available; its overexpression rescues mitochondrial translation and bioenergetic defects in frataxin-deficient cells [PMID:38199006]. Across the assembly pathway METTL17 binds the mt-SSU early and serves as a platform for Mettl15 recruitment before being released to permit progression of pre-mitoribosome maturation [PMID:bio_10.1101_2024.12.18.629302]. METTL17 abundance is set post-translationally by a SIRT5–RNF126 axis, in which SIRT5 desuccinylates K274 to facilitate RNF126-mediated K116 ubiquitination and degradation, tuning OXPHOS output [PMID:42021405].","teleology":[{"year":2019,"claim":"Established METTL17 as a mitochondrial SAM-binding factor required for small-subunit mitoribosome integrity, answering whether it has any role in mitochondrial gene expression.","evidence":"CRISPR knockout, subcellular fractionation, RNA-protein binding, SAM-binding and quantitative rRNA modification mapping, mitochondrial translation assays in human cells","pmids":["31487196"],"confidence":"High","gaps":["Did not demonstrate direct catalytic deposition of m4C840/m5C842 by METTL17","Stoichiometry and structural basis of mt-SSU binding not defined"]},{"year":2023,"claim":"Tested whether METTL17 is itself the methyltransferase for the 12S rRNA marks, addressing the catalytic-versus-regulatory question.","evidence":"MALDI-TOF mass spectrometry of a putative 12S rRNA substrate region","pmids":["38234605"],"confidence":"Low","gaps":["Negative/ambiguous result under single set of conditions; does not exclude activity in other contexts or with cofactors","No identification of the responsible enzyme if METTL17 is non-catalytic"]},{"year":2024,"claim":"Revealed that METTL17 carries an Fe-S cluster and acts as a checkpoint coupling Fe-S availability to OXPHOS protein translation, explaining how its stability and function are cofactor-gated.","evidence":"Quantitative proteomics, sequence analysis, mutagenesis, cryo-EM, and overexpression rescue in FXN-deficient cells","pmids":["38199006"],"confidence":"High","gaps":["Mechanism by which Fe-S occupancy is sensed and transmitted to translation not fully resolved","How the checkpoint discriminates Fe-S-rich transcripts not defined"]},{"year":2024,"claim":"Linked METTL17-dependent mitochondrial RNA methylation to redox homeostasis and ferroptosis sensitivity in cancer cells, extending its role beyond bioenergetics.","evidence":"Knockdown, epitranscriptomic profiling, ROS/lipid peroxidation assays, xenograft and AOM/DSS CRC models","pmids":["38377789"],"confidence":"Medium","gaps":["Direct versus indirect basis for the broad m4C/m5C/m3C/m7G/m6A changes not established","Causal chain from translation defect to ferroptosis not dissected"]},{"year":2025,"claim":"Defined a post-translational control circuit (SIRT5 desuccinylation of K274 enabling RNF126 ubiquitination of K116) that sets METTL17 levels and downstream ETC component expression.","evidence":"Reciprocal Co-IP, mass spectrometry, site-directed mutagenesis, bioenergetic assays, and xenografts; single lab","pmids":["42021405"],"confidence":"Medium","gaps":["Physiological signals that regulate SIRT5/RNF126 activity toward METTL17 unknown","Whether degradation is coordinated with the Fe-S checkpoint not addressed"]},{"year":2025,"claim":"Provided a structural mechanism placing METTL17 as an early-assembly platform for Mettl15 recruitment, integrating early and late pre-mitoribosome maturation.","evidence":"Cryo-EM (T. brucei) and molecular dynamics integrated with mammalian homolog data (preprint)","pmids":["bio_10.1101_2024.12.18.629302"],"confidence":"Medium","gaps":["Preprint, not yet peer-reviewed","Trigger for METTL17 release and conservation of the exact choreography in humans not confirmed"]},{"year":2025,"claim":"Reported extramitochondrial associations of METTL17 with STAT1 mRNA methylation and JAK/STAT signaling in immune and cancer contexts.","evidence":"MeRIP, knockdown, flow cytometry, docking, and xenograft models","pmids":["39957595","41005192"],"confidence":"Low","gaps":["No site-specific modification mapping or rescue; mechanistic link to the mitoribosomal function not established","Pathway placement inferred from downstream markers"]},{"year":null,"claim":"Whether METTL17 itself deposits the 12S mt-rRNA marks or acts purely as a scaffold/checkpoint, and how its Fe-S sensing is mechanistically coupled to translational licensing, remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["Direct catalytic activity unconfirmed","Sensing-to-translation transduction mechanism undefined","Reconciliation of mitochondrial role with reported cytoplasmic mRNA-methylation claims missing"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003723","term_label":"RNA binding","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[0]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,1]}],"complexes":["mitoribosomal small subunit (mt-SSU)"],"partners":["MTTL15","SIRT5","RNF126"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9H7H0","full_name":"Ribosome assembly protein METTL17, mitochondrial","aliases":["False p73 target gene protein","Methyltransferase 11 domain-containing protein 1","Methyltransferase-like protein 17","Protein RSM22 homolog, mitochondrial"],"length_aa":456,"mass_kda":50.7,"function":"Mitochondrial ribosome (mitoribosome) assembly factor (PubMed:36482135, PubMed:38199006). Binds at the interface of the head and body domains of the mitochondrial small ribosomal subunit (mt-SSU), occluding the mRNA channel and preventing compaction of the head domain towards the body (PubMed:36482135). Probable inactive methyltransferase: retains the characteristic folding and ability to bind S-adenosyl-L-methionine, but it probably lost its methyltransferase activity (PubMed:38234605)","subcellular_location":"Mitochondrion matrix","url":"https://www.uniprot.org/uniprotkb/Q9H7H0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/METTL17","classification":"Common Essential","n_dependent_lines":686,"n_total_lines":1208,"dependency_fraction":0.5678807947019867},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/METTL17","total_profiled":1310},"omim":[{"mim_id":"616091","title":"METHYLTRANSFERASE-LIKE 17; METTL17","url":"https://www.omim.org/entry/616091"},{"mim_id":"602628","title":"FORKHEAD BOX N3; FOXN3","url":"https://www.omim.org/entry/602628"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Nucleoplasm","reliability":"Enhanced"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/METTL17"},"hgnc":{"alias_symbol":["FLJ20859"],"prev_symbol":["METT11D1"]},"alphafold":{"accession":"Q9H7H0","domains":[{"cath_id":"-","chopping":"30-54_385-442","consensus_level":"medium","plddt":82.9966,"start":30,"end":442},{"cath_id":"3.40.50.150","chopping":"62-80_150-375","consensus_level":"high","plddt":94.4707,"start":62,"end":375},{"cath_id":"1.10.10","chopping":"102-140","consensus_level":"medium","plddt":87.6582,"start":102,"end":140}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H7H0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H7H0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H7H0-F1-predicted_aligned_error_v6.png","plddt_mean":85.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=METTL17","jax_strain_url":"https://www.jax.org/strain/search?query=METTL17"},"sequence":{"accession":"Q9H7H0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9H7H0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9H7H0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H7H0"}},"corpus_meta":[{"pmid":"38377789","id":"PMC_38377789","title":"METTL17 coordinates ferroptosis and tumorigenesis by regulating mitochondrial translation in colorectal cancer.","date":"2024","source":"Redox biology","url":"https://pubmed.ncbi.nlm.nih.gov/38377789","citation_count":81,"is_preprint":false},{"pmid":"31487196","id":"PMC_31487196","title":"Mettl17, a regulator of mitochondrial ribosomal RNA modifications, is required for the translation of mitochondrial coding genes.","date":"2019","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/31487196","citation_count":50,"is_preprint":false},{"pmid":"38199006","id":"PMC_38199006","title":"METTL17 is an Fe-S cluster checkpoint for mitochondrial translation.","date":"2024","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/38199006","citation_count":41,"is_preprint":false},{"pmid":"24137763","id":"PMC_24137763","title":"Sequence variants in four candidate genes (NIPSNAP1, GBAS, CHCHD1 and METT11D1) in patients with combined oxidative phosphorylation system deficiencies.","date":"2010","source":"Journal of inherited metabolic disease","url":"https://pubmed.ncbi.nlm.nih.gov/24137763","citation_count":17,"is_preprint":false},{"pmid":"38234605","id":"PMC_38234605","title":"Testing a Hypothesis of 12S rRNA Methylation by Putative METTL17 Methyltransferase.","date":"2023","source":"Acta naturae","url":"https://pubmed.ncbi.nlm.nih.gov/38234605","citation_count":6,"is_preprint":false},{"pmid":"40250487","id":"PMC_40250487","title":"Demethylzeylasteral inhibits osteosarcoma cell proliferation by regulating METTL17-mediated mitochondrial oxidative phosphorylation.","date":"2025","source":"Toxicology and applied pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/40250487","citation_count":3,"is_preprint":false},{"pmid":"41005192","id":"PMC_41005192","title":"Bufalin targeting METTL17 inhibits the occurrence and metastasis of oral cancer through JAK1/STAT3 signaling pathway.","date":"2025","source":"European journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/41005192","citation_count":3,"is_preprint":false},{"pmid":"39957595","id":"PMC_39957595","title":"METTL17-Mediated Inhibition of M1 Macrophage Polarization Alleviates the Progression of Ankylosing Spondylitis.","date":"2025","source":"Critical reviews in eukaryotic gene expression","url":"https://pubmed.ncbi.nlm.nih.gov/39957595","citation_count":3,"is_preprint":false},{"pmid":"41766913","id":"PMC_41766913","title":"Integrative omics and experimental validation reveal METTL17 and SLC27A1 as biomarkers and potential therapeutic targets in chronic kidney disease.","date":"2026","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/41766913","citation_count":0,"is_preprint":false},{"pmid":"42021405","id":"PMC_42021405","title":"SIRT5-RNF126 coordinated regulation of METTL17 stability controls mitochondrial function and glioma progression.","date":"2026","source":"Cell & bioscience","url":"https://pubmed.ncbi.nlm.nih.gov/42021405","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.12.18.629302","title":"Mettl15-Mettl17 modulates the transition from early to late pre-mitoribosome","date":"2025-01-04","source":"bioRxiv","url":"https://doi.org/10.1101/2024.12.18.629302","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7723,"output_tokens":2461,"usd":0.030042,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9553,"output_tokens":2787,"usd":0.05872,"stage2_stop_reason":"end_turn"},"total_usd":0.088762,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2019,\n      \"finding\": \"METTL17 localizes to mitochondria via an N-terminal targeting sequence, specifically interacts with 12S mitochondrial ribosomal RNA (mt-rRNA) and small subunit mitoribosomal proteins (MSSUs), and is an S-adenosyl methionine (SAM)-binding protein. Loss of METTL17 reduces m4C840 (~70%) and m5C842 (~50%) modifications on 12S mt-rRNA, identifying METTL17 as the first known regulator of m4C840. METTL17 loss destabilizes 12S mt-rRNA and associated MSSU proteins, impairing mitochondrial ribosome function and translation of mitochondrial protein-coding genes in a SAM-binding-dependent manner, causing defects in oxidative phosphorylation.\",\n      \"method\": \"CRISPR knockout screen, subcellular fractionation/localization, RNA-protein interaction assays, SAM-binding assays, mass spectrometry-based RNA modification quantification, mitochondrial translation assays, metabolomics\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (localization, RNA binding, biochemical SAM-binding, quantitative modification mapping, translation assays) in a single focused study\",\n      \"pmids\": [\"31487196\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"METTL17 binds to the mitoribosomal small subunit (mt-SSU) during late assembly and harbors a previously unrecognized [Fe4S4]2+ cluster required for its stability. Loss of the Fe-S cluster destabilizes METTL17. METTL17 acts as an Fe-S cluster checkpoint: it promotes translation of Fe-S cluster-rich OXPHOS proteins only when Fe-S cofactors are available. METTL17 overexpression rescued mitochondrial translation and bioenergetic defects in frataxin (FXN)-deficient cells.\",\n      \"method\": \"Quantitative proteomics, comparative sequence analysis, site-directed mutagenesis, biochemical assays, cryo-electron microscopy (cryo-EM), overexpression rescue experiments\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure, mutagenesis, biochemistry, and functional rescue in a single rigorous study with multiple orthogonal methods\",\n      \"pmids\": [\"38199006\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"METTL17 governs mitochondrial RNA methylation (including m4C, m5C, m3C, m7G, and m6A marks) in colorectal cancer cells. METTL17 inhibition reduces these modifications, impairs translation of mitochondrial protein-coding genes, disrupts mitochondrial function and energy metabolism, and increases intracellular and mitochondrial lipid peroxidation and ROS, sensitizing cells to ferroptosis.\",\n      \"method\": \"siRNA/shRNA knockdown, MeRIP/epitranscriptomic profiling, mitochondrial translation assays, ROS/lipid peroxidation measurement, xenograft tumor models, AOM/DSS-induced CRC model\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple functional readouts and in vivo models, single lab, mechanistic interpretation relies partly on prior work\",\n      \"pmids\": [\"38377789\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Using MALDI-TOF mass spectrometry, direct methyltransferase activity of METTL17 on a 12S rRNA target region during mitoribosome assembly was tested. The results did not confirm direct methyltransferase activity of METTL17 on this substrate under the conditions tested, suggesting METTL17 may regulate modifications indirectly rather than as a direct methyltransferase.\",\n      \"method\": \"MALDI-TOF mass spectrometry of putative METTL17 substrate (12S rRNA region)\",\n      \"journal\": \"Acta naturae\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single method, single lab, negative/ambiguous result about direct enzymatic activity\",\n      \"pmids\": [\"38234605\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"METTL17 stability is regulated post-translationally through a SIRT5-RNF126 axis: the E3 ubiquitin ligase RNF126 ubiquitinates METTL17 at K116, targeting it for degradation, while SIRT5 acts as a desuccinylase removing succinylation at K274 of METTL17, thereby facilitating RNF126-mediated ubiquitination and degradation. METTL17 sustains mitochondrial OXPHOS by positively regulating electron transport chain components NDUFA2, NDUFS1, SDHB, UQCRB, and MT-CO2.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, lentiviral knockdown/overexpression, site-directed mutagenesis (K116, K274), ATP/ROS/mitochondrial membrane potential assays, xenograft tumor models\",\n      \"journal\": \"Cell & bioscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, mass spectrometry, mutagenesis of modification sites, functional rescue; single lab\",\n      \"pmids\": [\"42021405\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"METTL17 promotes RNA methylation of STAT1 mRNA, inhibiting STAT1 mRNA and protein stability, thereby suppressing M1 macrophage polarization and inflammatory response. METTL17 knockdown promoted M1 macrophage polarization and enhanced inflammatory signaling.\",\n      \"method\": \"RT-qPCR, MeRIP assay, Western blot, flow cytometry, EdU proliferation assay, siRNA knockdown\",\n      \"journal\": \"Critical reviews in eukaryotic gene expression\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, limited mechanistic validation, MeRIP without site-specific mapping or rescue of specific modification\",\n      \"pmids\": [\"39957595\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Structural and molecular dynamics analysis of Mettl15 and Mettl17 in Trypanosoma brucei integrated with mammalian homolog data reveals that Mettl17 binds the mt-SSU at an early assembly stage and acts as a platform for Mettl15 recruitment. Release of Mettl17 allows a conformational change of Mettl15 for substrate recognition, and after methylation Mettl15 adopts a loosely bound state leading to its replacement by initiation factors, linking early and late pre-mitoribosome assembly stages.\",\n      \"method\": \"Cryo-EM structural data (T. brucei), molecular dynamics simulations, integration with mammalian homolog structural data\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — structural data plus MD simulations, model organism (T. brucei) with mammalian integration; preprint, not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2024.12.18.629302\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"METTL17 interacts directly with bufalin (identified by human proteomic microarray and molecular docking), and METTL17 promotes oral cancer progression in vitro and in vivo through activation of the JAK1/STAT3 signaling pathway. Bufalin downregulates METTL17 expression and reverses its pro-tumorigenic effects.\",\n      \"method\": \"Human proteomic microarray, molecular docking, CCK-8, wound healing, transwell, Western blot, in vivo xenograft\",\n      \"journal\": \"European journal of medicinal chemistry\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, pathway placement inferred from downstream markers without direct mechanistic link between METTL17 mitoribosomal function and JAK1/STAT3\",\n      \"pmids\": [\"41005192\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"METTL17 is a mitochondria-localized SAM-binding protein that associates with the mitoribosomal small subunit (mt-SSU) during late assembly, harbors a [Fe4S4]2+ cluster essential for its stability, regulates m4C840 and m5C842 modifications on 12S mt-rRNA (and possibly additional marks), and acts as an Fe-S cluster checkpoint that licenses translation of OXPHOS proteins only when Fe-S cofactors are available; its stability is further controlled post-translationally by SIRT5-mediated desuccinylation at K274 and RNF126-mediated K116 ubiquitination, and in the broader assembly pathway it cooperates with Mettl15 by serving as a platform for Mettl15 recruitment before being released to allow progression to late assembly.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"METTL17 is a mitochondria-localized, SAM-binding protein that supports assembly and function of the mitoribosomal small subunit and thereby enables translation of mitochondrially-encoded OXPHOS components [#0, #1]. It is imported via an N-terminal targeting sequence, binds 12S mt-rRNA and small-subunit mitoribosomal proteins during late assembly, and its loss destabilizes 12S mt-rRNA and associated proteins, impairing mitochondrial translation and oxidative phosphorylation in a SAM-binding-dependent manner [#0]. METTL17 loss reduces the m4C840 and m5C842 modifications on 12S mt-rRNA, identifying it as the first known regulator of m4C840, although a dedicated test of direct methyltransferase activity on the 12S region did not confirm catalysis, indicating it may govern these marks indirectly [#0, #3]. METTL17 harbors a [Fe4S4]2+ cluster required for its own stability and functions as an Fe-S cluster checkpoint that licenses translation of Fe-S-rich OXPHOS proteins only when Fe-S cofactors are available; its overexpression rescues mitochondrial translation and bioenergetic defects in frataxin-deficient cells [#1]. Across the assembly pathway METTL17 binds the mt-SSU early and serves as a platform for Mettl15 recruitment before being released to permit progression of pre-mitoribosome maturation [#6]. METTL17 abundance is set post-translationally by a SIRT5–RNF126 axis, in which SIRT5 desuccinylates K274 to facilitate RNF126-mediated K116 ubiquitination and degradation, tuning OXPHOS output [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2019,\n      \"claim\": \"Established METTL17 as a mitochondrial SAM-binding factor required for small-subunit mitoribosome integrity, answering whether it has any role in mitochondrial gene expression.\",\n      \"evidence\": \"CRISPR knockout, subcellular fractionation, RNA-protein binding, SAM-binding and quantitative rRNA modification mapping, mitochondrial translation assays in human cells\",\n      \"pmids\": [\"31487196\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not demonstrate direct catalytic deposition of m4C840/m5C842 by METTL17\", \"Stoichiometry and structural basis of mt-SSU binding not defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Tested whether METTL17 is itself the methyltransferase for the 12S rRNA marks, addressing the catalytic-versus-regulatory question.\",\n      \"evidence\": \"MALDI-TOF mass spectrometry of a putative 12S rRNA substrate region\",\n      \"pmids\": [\"38234605\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Negative/ambiguous result under single set of conditions; does not exclude activity in other contexts or with cofactors\", \"No identification of the responsible enzyme if METTL17 is non-catalytic\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Revealed that METTL17 carries an Fe-S cluster and acts as a checkpoint coupling Fe-S availability to OXPHOS protein translation, explaining how its stability and function are cofactor-gated.\",\n      \"evidence\": \"Quantitative proteomics, sequence analysis, mutagenesis, cryo-EM, and overexpression rescue in FXN-deficient cells\",\n      \"pmids\": [\"38199006\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which Fe-S occupancy is sensed and transmitted to translation not fully resolved\", \"How the checkpoint discriminates Fe-S-rich transcripts not defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Linked METTL17-dependent mitochondrial RNA methylation to redox homeostasis and ferroptosis sensitivity in cancer cells, extending its role beyond bioenergetics.\",\n      \"evidence\": \"Knockdown, epitranscriptomic profiling, ROS/lipid peroxidation assays, xenograft and AOM/DSS CRC models\",\n      \"pmids\": [\"38377789\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus indirect basis for the broad m4C/m5C/m3C/m7G/m6A changes not established\", \"Causal chain from translation defect to ferroptosis not dissected\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined a post-translational control circuit (SIRT5 desuccinylation of K274 enabling RNF126 ubiquitination of K116) that sets METTL17 levels and downstream ETC component expression.\",\n      \"evidence\": \"Reciprocal Co-IP, mass spectrometry, site-directed mutagenesis, bioenergetic assays, and xenografts; single lab\",\n      \"pmids\": [\"42021405\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological signals that regulate SIRT5/RNF126 activity toward METTL17 unknown\", \"Whether degradation is coordinated with the Fe-S checkpoint not addressed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Provided a structural mechanism placing METTL17 as an early-assembly platform for Mettl15 recruitment, integrating early and late pre-mitoribosome maturation.\",\n      \"evidence\": \"Cryo-EM (T. brucei) and molecular dynamics integrated with mammalian homolog data (preprint)\",\n      \"pmids\": [\"bio_10.1101_2024.12.18.629302\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer-reviewed\", \"Trigger for METTL17 release and conservation of the exact choreography in humans not confirmed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Reported extramitochondrial associations of METTL17 with STAT1 mRNA methylation and JAK/STAT signaling in immune and cancer contexts.\",\n      \"evidence\": \"MeRIP, knockdown, flow cytometry, docking, and xenograft models\",\n      \"pmids\": [\"39957595\", \"41005192\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No site-specific modification mapping or rescue; mechanistic link to the mitoribosomal function not established\", \"Pathway placement inferred from downstream markers\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether METTL17 itself deposits the 12S mt-rRNA marks or acts purely as a scaffold/checkpoint, and how its Fe-S sensing is mechanistically coupled to translational licensing, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Direct catalytic activity unconfirmed\", \"Sensing-to-translation transduction mechanism undefined\", \"Reconciliation of mitochondrial role with reported cytoplasmic mRNA-methylation claims missing\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": []},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": []}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [\"mitoribosomal small subunit (mt-SSU)\"],\n    \"partners\": [\"MTTL15\", \"SIRT5\", \"RNF126\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}